Common difficulties associated with use of bioactive materials in a variety of industries are mainly based on loss of activity with time or with decomposition or inactivation upon contact with one or more environmental conditions such as hear and chemicals. The difficulties are greater where the bioactive material is intended for biomedical or therapeutic applications. Destruction or inactivation of the bioactive en route to site of disease is a particular difficulty where enzymes are concerned.
One of methods of protection which have been used extensively involves encapsulation of the bioactive in a material matrix which protects the bioactive from heat, light, oxygen as well as from decomposition when in contact with biological entities within the human body.
Alumina is the only metal oxide which is currently approved for injection to a human subject. Organic and bio-organic doping of alumina sol-gel is much less developed than the corresponding silica-based chemistry, but examples for entrapment of small molecules [1] and of enzymes [2-4], and E. coli [5], exist.